In recent years, the mechanism by which mammalian immune systems, such as human and murine systems react to infections, foreign antigens, and to so-called "self antigens" in connection with autoimmune diseases has begun to be established. See, in this regard, Grey et al., Scientific American 261(5): 56-64 (1989); Male et al., Advanced Immunology (J. P. Lippincott Company, 1987), especially chapters 6 through 10.
Well known, both to the skilled artisan and to the general public is the role of antibodies, sometimes referred to as "immunoglobulin" or the less correct and older "gammaglobulin" in response to infection. Antibodies are protein molecules which are produced by B cells in response to infection. It is well known that these antibodies act to "disable" or to inactivate infectious agents in the course of combating the infection.
In order for antibodies to be produced, however, preceding events must occur which lead to stimulation of the B cells which produce the antibodies. One of the key events involved in the processes leading to antibody production is that of antigen recognition. This aspect of the immune response requires the participation of so-called "T-cells", and is less well known than the antibody response commented on supra.
Briefly, and in outline form, antigen recognition requires interaction of an "antigen presentation cell", a "processed antigen", and a T-cell. See Grey and Male, supra. The "processed antigen", in an infection, is a molecule characteristic of the pathogen which has been treated, i.e., "processed", by other cells which are a part of the immune system. The processed antigen interacts with a receptor on the surface of an antigen presented in a manner not unlike a lock fitting into a key hole or, perhaps more aptly, two pieces of a jigsaw puzzle.
The configuration of the complex processed antigen and receptor on antigen presentation cell allows the participation of T-cells. T-cells do not join the complex unless and until the processed antigen has fit into the receptor on the antigen presentation cell. This receptor will hereafter be referred to by its scientific name, the major histocompatibility complex (MHC), or the human leukocyte antigen (HLA). Generally, MHC is used to refer to murine systems, and HLA to humans.
These receptors fall into two classes. MHC-II molecules are involved in most responses to pathogens. In contrast, MHC-I molecules are involved when the pathogen is a virus, or a malignant cell is involved. When MHC-I participation is involved, there is no antibody stimulation; rather, the interaction of MHC-I, processed antigen and T-cell leads to lysis of cells infected with the pathogen.
The foregoing discussion has focused on the events involved in responding to "infection", i.e., the presence of pathogenic foreign material in the organism. Similar mechanisms are involved in autoimmune diseases as well. In these conditions, the organism treats its own molecules as foreign, or as "self-antigens". The same type of complexing occurs as described supra, with an antibody response being mounted against the organism itself. Among the diseases in which this is a factor are rheumatoid arthritis, diabetes, systemic lupus erythrematosis, and others.
The ability of the T-cell to complex with the processed antigen and MHC/HLA complex is dependent on what is referred to as the T-cell antigen receptor, referred to as "TCR" hereafter. The TCR is recognized as a heterodimer, made up of alpha (.alpha.) and beta (.beta.) chains. Five variable elements, coded for by germline DNA and known as "V.alpha., J.alpha., V.beta., and J.beta..sub.3, and D.beta. " as well as non-germline encoded amino acids contribute to the TCR. See, in this regard, Marrack et al., Immunol. Today 9: 308-315 (1988); Toyonaga et al., Ann. Rev. Immunol. 5: 585-620 (1987); Davis, Ann. Rev. Immunol. 4: 529-59 (1985); Hendrick et al., Cell 30: 141-152 (1982). With respect to the binding of TCR with processed antigen and MHC, see Babbitt et al., Nature 317: 359-361 (1985); Buus et al., Science 235: 1353-1358 (1987); Townsend et al., Cell 44: 959-968 (1986); Bjorkman et al., Nature 329: 506-512 (1987).
Generally, both the alpha and beta subunits are involved in recognition of the ligand formed by processed antigen and MHC/HLA molecule. This is not always the case, however, and it has been found that so-called "superantigens" stimulate T-cells with a particular V.beta. element, regardless of any other element. See Kappler et al., Cell 49: 273-280 (1987); Kappler et al., Cell 49: 263-271 (2987); MacDonald et al., Nature 332: 40-45 (1988); pullen et al., Nature 335: 796-801 (1988); Kappler et al., Nature 332: 35-40 (1988); Abe et al., J. Immunol. 140: 4132-4138 (1988); White et al , Cell 56: 27-35 (1989); Janeway et al., Immunol. Rev. 107: 61-88 (1989); Berkoff et al., J. Immunol. 139: 3189-3194 (1988), and Kappler et al., Science 244: 811-813 (1989).
The "superantigens" mentioned supra, while generally stimulating T-cells as long as they possess a V.beta. element, are somewhat specific in terms of the particular form of the V.beta. moiety which is present on the stimulated T cell.
Rheumatoid arthritis ("RA") is an autoimmune disease characterized by chronic inflammation of multiple joints. Mononuclear cell infiltration of the synovial membrane can lead eventually to the destruction of articular cartilage and surrounding structures. Because of its high frequency and potentially severe nature, this disease is a major cause of chronic disability in adults. Although the pathogenesis of RA and other similar autoimmune diseases remains unknown, both genetic and environmental factors have been implicated. Several lines of evidence suggest that T cells specific for self-antigens may play a critical role in the initiation of these diseases. In the case of RA, the linkage of the disease to the DR4 and DRI alleles of the Class II genes of the major histocompatibility complex (MHC) and the finding of sometimes oligoclonal, activated CD4.sup.+ T cells in synovial fluid and tissue of affected joints (Stastny et al., New Engl. J. Med. 298: 869 (1976); Gibofsky et al., J. Exp. Med. 148: 1728 (1978); McMichael et al., Arth. Rheum. 20: 1037 (1977); Schiff et al., Ann. Rheum. Dis. 41: 403 (1982 ); Duquesnoy et al., Hum. Immunol. 10: 165 (1984); Legrand et al., Am. J. Hum. Genet. 36: 690 (1984); Gregerse et al., Arth. Rheum. 30: 1205 (1987); Nepon et. al., Arth. Rheum 32: 15 (1989); Burmester et al., Arth. Rheum. 24: 1370 (1981); Fox et al., J. Immunol. 128: 351 (1982); Hemler et al., J. Clin. Invest. 78: 696 (1986); Stamenkoic et al., Proc. Natl. Acad. Sci. U.S.A. 85: 1179 (1988) suggest the involvement of CD4.sup.+, .alpha..beta.TCR-bearing, Class II-restricted T cells in the disease. This view is supported by the finding that partial elimination or inhibition of T cells by a variety of techniques can lead to an amelioration of disease in certain patients (Paulus et al., Arth. Rheum. 20: 1249 (1977); Karsh et al., Arth. Rheum. 22: 1055 (1979); Kotzin et al., N. Eng. J. Med. 30: 969 (1989); Trentham et al., N. Eng. J. Med. 305: 976 (1989); Herzog et al., Lancet ii: 1461 (1987); Yocum et al., Ann. Int. Med. 109: 863 (1989).
Usually, potentially autoreactive T cells are deleted or inactivated by encounter with self-antigen during their development, before they can damage the individual (Kappler et. all, Cell 49: 273 (1987); Marrack et al., Nature 332: 840 (1988); Kappler et al., Nature 32: 35 (1988); MacDonald et al., Nature 332: 40 (1988); Pullen et al., Nature 35: 796 (1988); Bill et al., J. Exp. Med. 169: 1405 (1989); Kisielow et al., Nature 333: 742 (1988); Ramsdell et al. Science 246: 1038 (1989). In order to understand autoimmunity one must understand how self-reactive T cells escape these processes to become part of the mature T cell pool and what factors control whether these cells will remain quiescent or become activated to induce autoimmune disease. One suggested scenario has been that a self-antigen which is sequestered, at very low levels or presented on inappropriate cells may fail both to remove specific T cells during development and to activate these cells once they mature. Occasionally, however, microbial antigens cross-reactive with the self-antigens may lead to activation of these specific T cells. Once activated these cells may now recognize and chronically respond to the previously ignored self-antigen, leading to autoimmune disease. One difficulty with this suggestion is the low probability of a cross-reaction between two infrequently recognized antigens. However, recently a set of unusual microbial antigens, i.e., the superantigens have been identified (Kappler et al., supra; Marrack et al., supra; Kappler et al., Science 244: 811 (1989); Marrack et al., Science 248: 705 (1990); White et al., Cell 56: 27 (1989); Tomai et al., J. Exp. Med. 172: 359 (1990); Choi et al., J. Exp. Med. 172: 981 (190); Marrack et al., Nature 349: 524 (1991); Frankel et al., Nature 349: 526 (1991); Woodland et al., Nature 349: 529 (191); Dyson et al., Nature 349: 531 (1991). Because superantigens engage virtually all T cells whose TCR bears a particular V.beta. they can effect a much larger number of T cells than conventional antigenic peptides, which require target T cells to bear the correct versions of all the TCR variable elements (V.alpha., J.alpha., V.beta., D.beta., J.beta.). Superantigens are, therefore, statistically more likely than conventional microbial antigens to crossreact with self-antigens and it has been suggested that they may play a role in induction of autoimmunity (Marrack et al., Science 248: 705 (1990).
It has now been found that T cells carrying specific V.beta. elements are associated with different pathological conditions. In Ser. No. 437,370, it was shown that infection by a superantigen presenting organism could be detected and diagnosed by assaying for particular V.beta. elements in a T cell containing sample. In U.S. Pat. No. 488,353, this phenomenon was shown to be true for toxic shock related disorders as well.
It has also been found that specific V.beta. elements can be associated with autoimmune disease, including rheumatoid arthritis. It has been found, quite surprisingly, that T cell populations and subpopulations are implicated and/or involved in autoimmune disorders, and it is possible to identify these and to correlate their presence to particular autoimmune diseases. This, in part, is the subject of the invention.
It has also been found that, within T cell containing samples, evident of "clonality", a term which is explained infra, is also evident of an autoimmune disorder. The invention, in general, thus relates to a method for assaying for V.beta. elements in T cell containing body fluid samples. The levels obtained are compared to levels in normal individuals, and variation from the normal is an indication of an autoimmune condition.